— In the early 1740′s, Benjamin Huntsman (U.K.) conceived the idea of melting cemented steel* in a crucible to improve the homogeneity of the metal because of the difficulty he was having with clock springs.
and while it was fluid skim off slag, then pour the metal into a mold and let it solidify into a mass which could be worked into the desired shapes.
—Huntsman’s method gave a steel which was uniform throughout and free from slag and dirt. It was at once apparent that the crucible steel was superior to cemented metal for many purposes.
—Since crucible method was not a purification process such as modern steel making, great care had to be taken in the selection of raw materials.
—Crucible process which is extinct now was only a melting and alloying process.
—High carbon steel may be made by melting wrought iron, scrap steel, and carbon in a barrel shaped graphite crucible (Fig. 27.4) 500 mm high and 300 mm in diameter. The desired hardness of the steel determines the amount of carbon to be placed in the crucible.
For alloy steels, materials such as tungsten and chromium are also placed in the crucible.
—Excellent quality tool steel was made in crucible furnaces, but since each crucible can hold only a small amount of metal, the process is slow, expensive and has been largely replaced by the electric furnace melting.
—Crucible steel was used to make
Knives and other weapons,
Components for various mechanisms.